1. Field of the Invention
This invention relates to air diffusers used in air distribution systems, specifically to improvements in method of installation, and adaptability to various size air ducts.
2. Description of Prior Art
Heretofore, installers of heating, air conditioning, and other types of air distribution systems would install an air diffuser in the following manner. A hole, slightly larger than the size of the opening (inlet) of the diffuser would be cut in the material (gypsum board, plaster, etc. in which the diffuser would be installed. A diffuser box, having one open end the same size as this hole, and a flange around this open end, would be placed into the hole from either side of the material and fastened in this position. The diffuser would then be placed over this prepared opening, and screws would be installed, through the screw holes in the diffuser, and into the flange of the diffuser box (usually requiring pre-drilling). In one of the remaining sides of the diffuser box, would be a hole or collar to accept the incoming air duct. This process is complicated and requires extensive labor.
U.S Pat. No. 4,858,520 to Prochnow and Burke (1989) describes one improvement to part of this process. It features a pre-fabricated housing with a plurality of lanced tabs which are driven outward into framework. However, this requires framework to support the assembly.
An improvement to the inlet portion of the diffuser box, cited in U.S. Pat. No. 3,866,950 to Skoch, Sigfried, and Slogick (1975) uses a multiple step configuration to receive a variety of air duct sizes. When connecting ducts larger than the smallest step, the unused portion is removed by breaking or cutting along a groove of reduced wall thickness. This is difficult to do without cutting, or removing needed portions. Because of the location of these grooves, further reduction of wall thickness (to make cutting easier) would substantially weaken the assembly.
A reference to a pawl mounting device (clip) exists in U.S. Pat. No. 4,297,525 to Bowden (1981). Although used on electrical boxes, this exact arrangement used on a larger or heavier structure would require additional support for the mounting screw, to eliminate any side to side movement of the mounting screw.